Sunday, March 28, 2010

Challenging P6 A001

Hi Ob,

Please help with this P6 question.

a) The long staircase at an HDB block has 300 steps. Michael climbed 3 steps at one go while his brother, Terry climbed 4 steps. If the steps both of them stepped on is counted once only, how many steps on the long staircase did they step on?

b) The long staircase at an HDB block has 300 steps. Michael climbed 3 steps at one go while his brother, Terry climbed 4 steps. How many steps on the long staircase did they step on?

MTIA.

A>

If the steps both of them stepped on is counted once only,...This basically refers to the number of common steps. The common steps are Common multiples of 3 and 4.3 x 4 = 12 300 ÷ 12 = 25 steps

a) They stepped on 25 steps.

How many steps on the long staircase did they step on?This basically refers to the total number of steps they stepped on. The steps are multiples of 3 and 4. But as there are common steps as found in (a), we need to remove it (otherwise there would be double-counting).300 ÷ 3 = 100300 ÷ 4 = 75